Spectroscopic sensors

Abstract

Disclosed herein are sensors that include: (a) a circuit board that includes an electronic processor; (b) a plurality of radiation sources, each source being attached to the circuit board; and (c) a spectral detector attached to the circuit board, the spectral detector being configured to analyze radiation derived from one or more of the plurality of radiation sources. During use, the sensors are configured to be worn on a portion of a body of a subject. The electronic processor is configured to cause two or more of the plurality of radiation sources to direct incident radiation to the subject, to cause the spectral detector to analyze radiation from the subject, and to determine one or more properties of the subject based on the radiation from the subject. Methods of making and using these sensors are also disclosed.

What is claimed is: 
     
       1. A sensor, comprising:
 a circuit board comprising an electronic processor; 
 a plurality of radiation sources, each source being mounted directly to the circuit board; and 
 a spectral detector attached to the circuit board, the spectral detector being configured to analyze radiation derived from one or more of the plurality of radiation sources, 
 wherein the plurality of radiation sources comprises a short-distance source positioned at a distance of 9 mm or less from the detector, and at least two long-distance sources each positioned at different distances at least 10 mm from the detector; and 
 wherein during operation of the sensor, the electronic processor is configured to:
 select one of the at least two long-distance sources by:
 (i) exposing a subject to incident radiation produced by one of the long-distance sources; 
 (ii) measuring reflected or transmitted radiation from the subject using the spectral detector; 
 (iii) repeating (i) and (ii) for each of the long-distance sources to generate spectral information corresponding to each of the long-distance sources; 
 (iv) comparing the spectral information for each of the long-distance sources to expected peak information to determine which ones of the long-distance sources are suitable for illumination of the subject; and 
 (v) selecting one of the suitable long-distance sources from (iv) based on acquisition times associated with the spectral information corresponding to each of the suitable long-distance sources; 
 
 expose the subject to incident radiation from the short-distance source and from the selected long-distance source and use the spectral detector to measure radiation from the subject corresponding to illumination by the short-distance source and the selected long-distance source; and 
 analyze the measured radiation to determine one or more properties of the subject. 
 
 
     
     
       2. The sensor of  claim 1 , wherein the electronic processor is configured to selectively adjust at least one of (i) a duty cycle of, and (ii) an electrical drive current supplied to, one or more of the plurality of radiation sources to produce incident radiation having a selected spectral shape. 
     
     
       3. The sensor of  claim 1 , wherein the plurality of radiation sources comprises at least two short-distance sources and at least three long-distance sources. 
     
     
       4. The sensor of  claim 1 , wherein the electronic processor is further configured to:
 calculate an absorbance spectrum for the subject corresponding to illumination of the subject by the short-distance source; 
 calculate an absorbance spectrum for the subject corresponding to illumination of the subject by the selected long-distance source; and 
 correct the absorbance spectrum corresponding to illumination by the long-distance source to reduce spectral effects due to layers of skin and fat in the subject using information derived from the absorbance spectrum corresponding to illumination by the short-distance source. 
 
     
     
       5. The sensor of  claim 1 , further comprising a display unit, wherein the display unit is positioned on a surface of the sensor opposite to a surface through which the incident radiation is emitted by the plurality of radiation sources, and wherein the display unit is configured to display values of at least some of the one or more properties of the subject and previously measured values of the one or more properties of the subject. 
     
     
       6. The sensor of  claim 1 , further comprising a communication interface comprising a wireless transmitter and receiver configured to transmit data to and from the sensor, wherein the sensor is configured to transmit the data over a network. 
     
     
       7. The sensor of  claim 1 , wherein the one or more properties comprise at least one of oxygen saturation, oxygen tension, pH, hematocrit, hemoglobin concentration, anaerobic threshold, water content, and oxygen consumption of the subject. 
     
     
       8. The sensor of  claim 1 , wherein the electronic processor is configured to maintain a non-zero measured detector signal intensity within a predetermined range of signal intensities during measurement of the radiation from the subject. 
     
     
       9. The sensor of  claim 8 , wherein the electronic processor is configured to maintain the detector signal intensity within a predetermined range by adjusting at least one of an electronic gain of the detector and a signal acquisition time to control the signal intensity. 
     
     
       10. The sensor of  claim 8 , wherein the electronic processor is configured to maintain the detector signal intensity within a predetermined range by selecting a different one of the plurality of radiation sources to direct incident radiation to the subject. 
     
     
       11. The sensor of  claim 1 , wherein the electronic processor is configured to provide information about the one or more properties of the subject to a therapeutic device to control the therapeutic device. 
     
     
       12. A sensor, comprising:
 a flexible mounting member comprising an adhesive surface configured to attach directly to a sample and to assume a shape corresponding to at least a portion of the sample when it attaches to the sample; 
 a rigid mounting member connected to the flexible mounting member; and 
 a plurality of radiation sources, a spectral detector, and an electronic processor mounted to the rigid mounting member, 
 wherein the plurality of radiation sources comprises a short-distance source positioned at a distance of 9 mm or less from the detector, and at least two long-distance sources positioned at a different distances at least 10 mm from the detector; and 
 wherein during operation of the sensor, the electronic processor is configured to:
 select one of the at least two long-distance sources by:
 (i) exposing the sample to incident radiation produced by one of the long-distance sources; 
 (ii) measuring reflected or transmitted radiation from the sample using the spectral detector; 
 (iii) repeating (i) and (ii) for each of the long-distance sources to generate spectral information corresponding to each of the long-distance sources; 
 (iv) comparing the spectral information for each of the long-distance sources to expected peak information to determine which ones of the long-distance sources are suitable for illumination of the sample; and 
 (v) selecting one of the suitable long-distance sources from (iv) based on acquisition times associated with the spectral information corresponding to each of the suitable long-distance sources; 
 
 expose the sample to incident radiation from the short-distance source and from the selected long-distance source and use the spectral detector to measure radiation from the sample corresponding to illumination by the short-distance source and the selected long-distance source; and 
 analyze the measured radiation to determine one or more properties of the sample. 
 
 
     
     
       13. The sensor of  claim 12 , wherein the flexible mounting member is disposable and at least partially transmissive to near-infrared radiation and forms a window through which incident radiation produced by the radiation sources passes to reach the sample. 
     
     
       14. The sensor of  claim 12 , wherein the one or more properties comprise at least one of oxygen tension, oxygen saturation, pH, hematocrit, hemoglobin concentration, anaerobic threshold, water content, and oxygen consumption of the sample. 
     
     
       15. A method for measuring one or more sample properties, the method comprising:
 selecting one of a plurality of long-distance radiation sources of a sensor, wherein each of the long-distance sources is positioned at a different distance at least 10 mm from a detector of the sensor, wherein the selecting comprises:
 (i) exposing the sample to incident radiation produced by one of the long-distance sources; 
 (ii) measuring reflected or transmitted radiation from the sample; 
 (iii) repeating (i) and (ii) for each of the long-distance sources to generate spectral information corresponding to each of the long-distance sources; 
 (iv) comparing the spectral information for each of the long-distance sources to expected peak information to determine which ones of the long-distance sources are suitable for illumination of the sample; and 
 (v) selecting one of the suitable long-distance sources from (iv) based on acquisition times associated with the spectral information corresponding to each of the suitable long-distance sources; 
 
 exposing the sample to incident radiation from a short-distance source positioned at a distance of 9 mm or less from the detector and from the selected long-distance source, and measuring radiation from the sample corresponding to illumination by the short-distance source and the selected long-distance source; and 
 analyzing the measured radiation to determine one or more sample properties. 
 
     
     
       16. The method of  claim 15 , further comprising:
 calculating an absorbance spectrum for the sample corresponding to illumination of the sample by the short-distance source; 
 calculating an absorbance spectrum for the sample corresponding to illumination of the sample by the selected long-distance source; and 
 correcting the absorbance spectrum corresponding to illumination by the long-distance source to reduce spectral effects due to skin and fat layers in the sample using information derived from the absorbance spectrum corresponding to illumination by the short-distance source. 
 
     
     
       17. The method of  claim 15 , further comprising, during measurement of radiation from the sample, maintaining an intensity of a detected radiation signal greater than zero and within a predetermined range of signal intensities. 
     
     
       18. The method of  claim 17 , wherein maintaining the signal intensity within a predetermined range comprises adjusting at least one of an electronic gain of a detector and a signal acquisition time during which the radiation is measured to control the signal intensity. 
     
     
       19. The method of  claim 17 , wherein maintaining the signal intensity within a predetermined range comprises using a different radiation source to direct radiation to the sample. 
     
     
       20. The method of  claim 15 , wherein the one or more sample properties comprise at least one of oxygen saturation, oxygen tension, pH, hematocrit, hemoglobin concentration, anaerobic threshold, water content, and oxygen consumption of the sample.